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Radio-wave signals in a car aerial
A car aerial receives radio waves from a radio transmitter.
Describe how the radio waves reaching the car aerial produce signals in the electrical circuit of the car radio.
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Study the marking See what earns credit and compare it with a full-mark answer.
Marking points
- 1 Say that the aerial absorbs the radio waves or their energy.
- 2 Say that electrons in the aerial are made to vibrate.
- 3 Say that this creates an alternating current in the aerial circuit.
- 4 Say that the electrical signal has the same frequency as the radio wave.
Full-mark answer
The aerial absorbs energy from the radio waves. This makes electrons in the aerial vibrate, producing an alternating current in the aerial circuit with the same frequency as the radio wave.
Why this answer loses marks
The radio waves are changed into sound waves in the aerial.
The mark scheme credits electrons vibrating and an alternating current signal, not direct conversion to sound in the aerial.